If you spend any time in the WordPress world, you've probably come across Zac Gordon. Zac is an enthusiastic and charming teacher who focuses on Javascript in WordPress. He borrowed the phrase "Learn Javascript Deeply" from Matt Mullenweg and he made it into his personal slogan.

For the last several years, Zac has produced video classes, online conferences, live talks, and podcasts that focus on teaching you how to use Javascript in WordPress.

I'm delighted to say we're working with Zac on a book, "React Explained". React is the library the WordPress team have chose for the new Gutenberg editor. They are not alone - both Drupal and Magento have also chosen React.

Zac is live-tweeting his writing progress at @zgordon on Twitter. You can also hear Zac talk about React on the OSTraining podcast.

In this extract from the book, Zac gives you a high-level overview of React and some key concepts.